CHM 1320
Assignment 6 Answers
1) Predict the major product(s) of the following reactions and give a mechanism to account for its
formation.
Note: For all answers, you can either assume HX will give H+ and X-, or you can explicity show the
breaking of the HX bond. The first method is used in answers here.
H
H X
X
For radical reactions, chain termination steps are not shown
+ HBr
a)
Br
H
H
b)
Br
+ HCl
Cl
H
H
+ HCl
1-methylcyclohexene
c)
Cl
Cl
H
H
d)
Cl
+ HBr
Br
H
H
Br
H
+
+
Br
Br
e)
H3PO4
1-methylcyclopentene
H2O
H
OH
H
H
OH2
1
OH2
OH
H3PO4
f)
H2O
H
Ph
H
OH
OH2
H
Ph
Ph
OH
Ph
H3PO4
g)
HO
H
O
H
HO
HO
H
OH2
H
AIBN
h)
+ HCl
∆
Initiation:
2
N N
CN
CN
CN
H Cl
NC
OH2
+ N2
Cl
+
NC
Propagation
Cl
Cl
Cl
H Cl
Cl
+
AIBN
i)
+ HBr
∆
Initiation:
2
N N
CN
CN
NC
CN
H Br
NC
+ N2
+
Br
Propagation
Br
Br
H Br
2
Br
+
Br
O
2) When 1, 3-butadiene reacts with HBr, a mixture of 3-bromo-1-butene and 1-bromo-2-butene is
obtained. Propose a mechanism to account for this observation.
H
H Br
H
+ Br
H
Br
Br
Br
H
H
Br
3) Propose a mechanism to account for the following:
H3PO4
OH
+
H2O
H
OH
H
OH
OH2
H
H
OH2
OH2
4) Predict the structures of products A and B in the following and give a mechanism to justify
your answer.
Hg(OAc)2
CH3OH
- OAc
AcO Hg OAc
A
NaBH4
B
H
O
Hg OAc
CH3OH
HgOAc
CH3OH
O
B
3
O
NaBH4
H
HgOAc
A
5) Predict the products of the following reactions:
+ Hg(OAc)2
a)
OH
H2O
HgOAc
b) the product from part (a) after treatment with NaBH4
OH
H
OEt
c)
HgOAc
EtOH
+ Hg(OAc)2
Cl
Cl
b) the product from part (c) after treatment with NaBH4
H
OEt
OEt
H
Cl
Cl
6) Predict the major products of the following transformations:
b)
BH2
+ BH3
a)
product from part (a) after treatment with H2O2 and NaOH
OH
c)
+ BH3
BH2
d)
product from part (c) after treatment with H2O2 and NaOH
OH
e)
f)
+ BH3
BH2
product from part (e) after treatment with H2O2 and NaOH
OH
g)
1) BH3
2) H2O2, NaOH
H
OH
4
HgOAc
OEt
Cl
7) Show how you could effect the following transformations:
1) Hg(OAc)2, H2O
a)
2) NaBH4
OH
or
H2O, H
1) Hg(OAc)2, EtOH
b)
O
2) NaBH4
or
EtOH, H
1) BH3
c)
OH
2) H2O2, NaOH
HBr
Br
d)
AIBN ∆
e)
H3PO4
HO
O
1) BH3
f)
2) H2O2, NaOH
OH
g)
OH
1) BH3
2) H2O2, NaOH
CH3SO2Cl
base
OH
O
O2
S
NaOH
OH
5
CH3
8) Predict the major products of the following reactions and give mechanisms to show how they
are formed.
Br2
a)
CCl4
Br
Br Br
Br
Br
Br
Br2
b)
CCl4
Br
Br
Br Br
Br
Br
Cl2
c)
CCl4
Cl
Cl Cl
Cl
Cl
Cl
2 I2
d)
CCl4
I
I
I
I
I
I
I
I
I
I
I
I
I2
e)
I
I
H2O
I
I
OH2
H2O
6
-H
I
OH
Br2
f)
H2O
Br
Br
Br
Br
Br
H
H2O
OH
H
OH
H2O
Br
Br2
g)
OH
OH
CH2Cl2
Br Br
Br
Br
OH
OH
H O
-H
Br
I
I Br
O
h)
Br
Br
I
9) Propose methods to accomplish the following transformations (most require >1 step):
Br
I
a)
Br
HI
NaOC(CH3)3
I
AIBN, ∆
H
Br
b)
OH
OH
H
CH3SO2Cl
OH
NaOEt
O
base
Br
Br2
H2O
SO2
OH
c)
Br
OH
OH
CH3SO2Cl
OH
base
H
O
Br2
NaOC(CH3)3
H2O
SO2
Br
OH
OH
d)
OH
CH3SO2Cl
OH
base
H
O
1) BH3
NaOC(CH3)3
2) H2O2, NaOH
SO2
7
OH
10) Show how you could prepare each of the following compounds starting with
methylenecyclohexane.
methylenecyclohexane
OH
a)
H3PO4
OH
H2O
Br
b)
HBr
Br
AIBN, ∆
OCH3
c)
1) Hg(OAc)2, CH3OH
OCH3
2) NaBH4
Cl
d)
OH
Cl2
Cl
OH
H2O
e)
OH
1) BH3
OH
2) H2O2
f)
O
mCPBA
O
8
HBr
g)
Br
OCH3
CH3OH
NaOEt
Br2
HBr
h)
Br
NaOEt
Br
mCPBA
O
H3O+
OH
OH
11) Propose a synthesis of each of the following starting with an alkene of your choice.
a)
OCH3
Retrosynthesis
+ CH3OH
OCH3
Synthesis
H
-H
CH3OH
H
OCH3
OCH3
b)
OH
Retrosynthesis
+ BH3
OH
Synthesis
H
+ BH3
H2O2
NaOH
Br
H
BH2
OH
c)
Br
Retrosynthesis
Br
+ Br2
Br
Synthesis
Br
Br Br
Br
9
Br
Br
Br
d)
Br
Retrosynthesis
Br
+ Br2
Br
double bond must be trans
Synthesis
Br
Br
Br
Br
Br
Br
12) Propose a synthesis of each of the following starting with alkenes containing 6 carbons or less.
You may use any additional reagents necessary, but all carbons in the products must be derived
from alkenes with <6 carbons.
10
a)
O
Retrosynthesis
O
HO
Synthesis
1) BH3
HO
2) H2O2, NaOH
H
H
HO
O
H
O
b)
O
Retrosynthesis
O
O
OH
SO2
CH3
HO
Synthesis
1) BH3
HO
O
2) H2O2, NaOH
CH3SO2Cl
1) BH3
2) H2O2, NaOH
OH
O
base
11
SO2
CH3
O
c)
Retrosynthesis
OH
O
Synthesis
H3PO4
OH
d)
O
O
Br
Retrosynthesis
Br
O
HO
Synthesis
H
H
HO
OH2
HO
H
Br Br
Br
HO
Br
Br
12
H
O
O